Effect of Nanofluid on Entropy Generation and Pumping Power in Coiled Tube

Vosough, Amir; Falahat, Alireza

doi:10.2514/1.t3771

Cited by 12 publications

(1 citation statement)

References 24 publications

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“…In practical operation, the NDDCT heat rejection rate is almost constant and tower underperformance manifests itself in higher water temperature [37,78]. Therefore, the first method is the preferred metric used in previous full-scale tests.…”

Section: Crosswind Effect On the Nddcthmentioning

confidence: 99%

Numerical and experimental study of small natural draft dry cooling tower for concentrating solar thermal power plant

Li¹

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The typically arid climates in the likely locations for renewable thermal power plants such as Concentrating Solar Thermal (CST) power plants provide the motivation for dry cooling technology applications. Natural draft dry cooling tower (NDDCT) with low maintenance cost and no parasitic power consumption offers a feasible and cost effective option for such applications. Compared with the conventional coal fired and nuclear power plants, the size of the CST power plant proposed for Australian regional communities is much smaller. However, the existing cooling tower design is optimised for large steam power plants, and is not optimal for these renewable power plants. (2) The performance of the experimental tower was tested at two constant heat loads of 600 kW and 840 kW, respectively, with various ambient temperatures. The 1D numerical model was refined and validated with the experimental data. The thermodynamic model of a 1 MW CST power plant running with sCO2 cycle was developed and integrated with the updated cooling tower model. Significant differences were observed between the steam Rankine and sCO2 cycles in terms of the effect of the ambient temperature on power generation. The differences between steam Rankine and sCO2 Brayton cycle in this context were analysed and discussed.(3) Two potential cooling issues with small NDDCT, the crosswind and the cold inflow, were identified and the detail experimental data were presented. The crosswind effect on small cooling tower is different from the conventional big cooling towers. With the increase of the crosswind speed, the overall cooling performance of the small NDDCT first decreases and then increases. The mixed convection theory and the Richardson Number were proposed to explain this phenomenon. On the other hand, repeated cold inflow events were observed during the tests, which cause a significant decrease of the air temperature inside the cooling tower. The water outlet temperature can be increased up to 3°C as a result of the cold inflow effect. Further analysis of the mechanism shows that the cold air incursion at the top of the cooling tower could decrease the driving force and also form an extra flow resistance for the airflow through the heat exchanger.(4) Based on the working mechanism of the air-cooled heat exchanger and the crosswind effect on NDDCT, this study proposed a new method to increase the cooling performance of NDDCT under crosswind conditions by optimizing the water mass flow rate in the air-cooled heat exchangers. By optimising the water distribution, the water outlet temperature of each heat exchanger is more uniform and the adversely influence of the crosswind can be effectively relieved.The findings in this paper can lay an important foundation for future small cooling tower design and operation.

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Section: Crosswind Effect On the Nddcthmentioning

confidence: 99%

Numerical and experimental study of small natural draft dry cooling tower for concentrating solar thermal power plant

Li¹

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Spatial entropy generation analysis for the design improvement of a single slope solar still

Rashidi

Esfahani

2017

Env Prog and Sustain Energy

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In the article, entropy generation is calculated locally by the computational fluid dynamic simulation for the design improvement of a single slope solar still. A numerical approach based on SIMPLE algorithm is utilized to simulate the double diffusive natural convection in the solar still and solve the mass, momentum, energy, and concentration equations. The study investigates the effects of aspect ratio and temperatures of glass cover and water on different types of entropy generation containing frictional, diffusive, and thermal entropy generations. Obtained results indicate that an increase in different types of entropy generation is occurred with an increase in the glass and water temperatures. Moreover, the still with higher aspect ratio creates higher values of entropy generation than that of still with smaller aspect ratio. For example, there is 30% increment in diffusive entropy generation when the aspect ratio value is changed from A = 2.58 to A = 5.3 for Tg=30°C and Tw=40°C. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1112–1120, 2018

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Triple-objective optimization of a double-tube heat exchanger with elliptic cross section in the presence TiO2 nanofluid

Khanmohammadi

Rahimi

Khanmohammadi

et al. 2019

J Therm Anal Calorim

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Effect of Nanofluid on Entropy Generation and Pumping Power in Coiled Tube

Cited by 12 publications

References 24 publications

Numerical and experimental study of small natural draft dry cooling tower for concentrating solar thermal power plant

Numerical and experimental study of small natural draft dry cooling tower for concentrating solar thermal power plant

Spatial entropy generation analysis for the design improvement of a single slope solar still

Triple-objective optimization of a double-tube heat exchanger with elliptic cross section in the presence TiO2 nanofluid

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